Atmospheric Angular Momentum (AAM), an index measuring the dynamic state of the general circulation, and the Length of day (LOD), a measure of the Earth’s rotation rate, both connected through the terrestrial angular momentum budget, are investigated for a possible connection with solar activity fluctuations from interannual to secular time scales. In addition, the southern oscillation index and records of sea surface temperature are used as proxy series in this analysis during the era prior to the availability of AAM analyses.
At interannual time scales, the variability in AAM and LOD agrees with that in solar activity with regard to the decadal cycle in the stratospheric quasi biennial oscillation and solar activity but whose phases are slowly shifting from one another with time, while the stratospheric quasi biennial cycle agrees with the solar quasi biennial cycle, though led by 6 years.
At decadal time scales, AAM varies statistically with the solar decadal cycle over much of the last century since 1930-1940. The decadal mode in AAM is suggested here to be generated by upward propagation of surface atmospheric modes, from the surface throughout the troposphere through the stratosphere.
The analysis of equatorial Sea Surface Temperature (SST) over the last three centuries (1730-2000) and that of LOD since 1830 confirm the agreement found over the last part of the 20th century, as well as the general disagreement before.